The present invention relates to an improved surveying method, and more particularly, to a laser surveying technique which can be used to accurately define all curves, grades or elevations.
Conventional surveying methods require the use of a surveyor's transit and a highly skilled operator. Each section of a curve to be surveyed is typically configured as a true radius. Each point thereon is located by two dimensions which are physically measured with respect to two centerlines.
The prior art methods which necessitate repetitive angular and linear measurements are susceptible to mistakes in measurements and miscalculations. Furthermore, the time required to accurately survey a given curve, grade or elevation may be inordinately lengthy and expensive.
Conventional laser systems are designed for a multitude of purposes have been generally commercially available since the 1960's. Basic refinements in these systems have included bulk reductions and the advent of the low power laser (with an output of the order of several milliwatts). With the compacting of laser technology, the number of practical laser applications have been compounded.
In the field of manufacturing alignment techniques, laser devices are firmly embedded for applications such as aligning avionic systems on sophisticated aircraft. One exemplary system which not only senses misalignment, but also allows accurate angular measurement of such displacement is described in the copending patent application "Triaxis Laser Alignment System" (Ser. No. 200,003 filed Oct. 23, 1980), assigned to the common assignee of this application.
Yet despite this increased application of laser devices, no one has heretofore proposed such a technique as the present invention which utilizes one or more diffracted laser patterns to enable surveying a curved roadway.
Accordingly, it is a principle object of the present invention to provide a method of surveying through the use of diffracted laser beams as to define a curved track, grade or super elevation.
It is another object of the present invention to provide a method of impinging two diffracted laser beams to create a grid which may be used to define the course of a curved track.
Yet another object of the invention is to provide a laser surveying method which requires only low operator skills to accurately define the curve, grade and elevation of a roadway, railway or waterway.
These and other objects and advantages of the present invention are accomplished by diffracting one or more laser light sources to cover the area to be surveyed. A reference line, such as a road straightaway centerline may be used to align the laser zero order beam. The curved road portion is plotted by colineating two fans of diffracted laser beams to form a grid from which the desired parabolic shape can be easily charted and marked.
Grade markings may be effected by regulating the angular orientation of the laser beam ruling as to define a desired angular plane with the fan of diffracted laser beams.
Elevational levels are determinable by vertically orienting the laser grating to define known vertical angular increments which can readily be translated into linear distances.
The curve radius, grade and elevation may accordingly be varied throughout the length of the curve to the most practical form for any given application. Transition curve sections may be readily mated by the best tailored fit.